Inspection Procedure 19
INSPECTION PROCEDURE 19: KnockingCOMMENT
- In cases such as the above, the cause is probably that the detonation control is defective or the heat value of the spark plug is inappropriate.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Defective knock sensor.
- Incorrect heat value of the spark plug.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Using the scan tool MB991958, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 2.
STEP 2. Check the ignition timing.
1. The ignition timing should retard more when knock sensor connector B-120 is disconnected than when it is connected.
Q: When the knock sensor connector B-120 was disconnected, was the ignition timing delayed?
YES : Check the following items, and repair or replace the defective items.
a. Check the spark plugs.
b. Fuel quality, octane level.
c. Check if the foreign materials (water, kerosene, etc.) got into fuel.
Then confirm that the malfunction symptom is eliminated.
NO : Refer to DTC P0325 - Knock Sensor Circuit. P0325